The present invention pertains to communication system failures and more particularly to automatic protection switching in such communication systems.
Communication system traffic is routed to a central point to perform the data transfer and switching functions. This central point is a mobile switching center. The mobile switching center is typically coupled to a digital cross connect switch on E1 or T1 links. The digital cross connect switch aggregates multiple T1/E1 interfaces to the optical SONET/SDH interfaces terminating at the network element. These features may be embedded into a single product which is sold by mobile switching system manufacturers.
Typically line equipment is coupled to the digital cross connect switch via OC3 links. These OC3 links may run considerable distances, for example.
All too frequently, these lines or fiber connections are severed by backhoes or other digging equipment and are covered by automatic protection switching standards. Automatic protection switching standards have been implemented into communication systems in order to alleviate the problems with failures due to lines being severed. Today's competitive markets demand that communication systems provide near continuous functionality. Therefore it is imperative that 99.999 percent of the time that the communication system smoothly handle data transmission.
When line terminal equipment fails down stream processing equipment will lose functionality until a number of failures occur. Typically, after a number of failures occur in each of the down stream payload processors, some sort of switch over from a working line terminal equipment to a protection line terminal equipment is made by the system. Typically there are a great many payload processors coupled to each line terminal equipment. When line terminal equipment fails, each communication payload processor will incur a number of faults before any kind of system fault detection and resolution occurs. Errors and faults will “pile up” for each of the down stream payload processors. In addition, the line termination equipment itself may fail.
The above scenario suffers from a detection process which is relatively slow. In addition, the down stream payload processors must wait for some indication of what alternative data routing they must perform in order to circumvent the errors and faults.
Accordingly, it would be highly desirable to have an arrangement to provide rapid seamless protection arrangement for faults due to line termination equipment failure.